Can't build turrets on walls

[Hiztaar]

I spent hours in researchs to unlock the last walls. After having built them, the game does not want me to build any turret on it saying "to close to another building".

Tried everywhere along the wall with all my available turrets... Nothing worked. So now, the first attack will be the last for my colony

My save file is here : https://www.dropbox.com/s/fubfissllq0du13/P2.2.zip?dl=0

Note : Compatible with the version released just now !

[Hatsune_Neko]

for now tier 5 walls don't seam to have attachment points for turrets.
tier 4 walls does how ever.